unthinkable
adjective
                                                                                                                            
                                                            un·think·able
                    
                                                                                                              
                                                                                                                                  ˌən-ˈthiŋ-kə-bəl  
                                                      
                                                          
            1
                    
                                          
              
          
                                                      : not capable of being grasped by the mind                                      
                
                    
2
                    
                                          
              
          
                                                      : being contrary to what is reasonable, desirable, or probable : being out of the question                                      
                
                    
Love words? Need even more definitions?
  
  Merriam-Webster unabridged




Share